Number of found documents: 172
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Thermomechanical Analysis of Electrically Conductive Adhesives
Mach, Pavel; Bušek, David; Polanský, Radek
2010 -
Mechanical properties of isotropic electrically conductive adhesives (ICAs) are mainly influenced by their formulation and thermal processing. Thermomechanical analysis of ICAs was used with the goal to find influence of addition of two types of nanoparticles, silver nanoballs and carbon nanotubes, and two types of curing processes, on air and in vacuum, on the glass transition temperature and storage modulus of bisphenol epoxy adhesives filled with silver flakes (70 to 80 % by weight). Specimens were formed as blocks. Three groups of specimens were fabricated: specimens of adhesives used as received and cured according to the recommendation of a supplier in air; specimens of adhesives used as received and cured according to the recommendation of a supplier in vacuum, specimens of the same adhesives added with low fraction (0,3 to 10 % by weight) of silver nanoballs, colloidal dispersion of silver, or carbon nanotubes. There were found differences in the glass transition temperatures and storage and loss moduli in dependence on the type of particles added into adhesive. It was also found that the adhesive cured in vacuum had lower thermal expansion coefficient and higher the storage and loss modulus in comparison with adhesive cured in air. Available in digital repository of ČVUT.
Thermomechanical Analysis of Electrically Conductive Adhesives

Mechanical properties of isotropic electrically conductive adhesives (ICAs) are mainly influenced by their formulation and thermal processing. Thermomechanical analysis of ICAs was used with the goal ...

Mach, Pavel; Bušek, David; Polanský, Radek
České vysoké učení technické v Praze, 2010

Thermal Ageing of Electrically Conductive Micro/Nano Adhesives
Mach, Pavel; Bušek, David
2010 -
Electrical as well as mechanical properties of electrically conductive adhesives can be modified by addition of different types of nanoparticles. It has been investigated if changes of the resistance of adhesive joints caused by thermal ageing will differ in dependence on the type of nanoparticles added into adhesives. It has been found that adhesive joints formed of adhesives modified such the way have the same dependence of the resistance on the conditions of thermal ageing. That means, that nanoparticles added into adhesive in concentration up to 2,5% b. w. does not cause changes of an ageing mechanism of adhesive matrix. Keywords: micro/nano adhesives; thermal ageing Available in digital repository of ČVUT.
Thermal Ageing of Electrically Conductive Micro/Nano Adhesives

Electrical as well as mechanical properties of electrically conductive adhesives can be modified by addition of different types of nanoparticles. It has been investigated if changes of the resistance ...

Mach, Pavel; Bušek, David
České vysoké učení technické v Praze, 2010

Comparison of Different Approaches of Manufacturing Process Optimization
Mach, Pavel; Barto, Seba
2010 -
There are many process variables, which more or less influence quality of a manufacturing process, and there are many parameters of a product, which constitute its quality. The control of variables of a manufacturing process for achievement of requested quality of a final product is a multi-parametric task. It is paid great effort to find such the way, which might lead to the most rapid solution. The use of full factorial experiments, fractional factorial experiments and Taguchi approach were compared from the point of view of number of experiments requested. It was found that the Taguchi orthogonal arrays are the most efficient method for higher number of process factors and that the full factorial experiments request the highest number of experiments from all methods under test. Keywords: full factorial experiments; fractional factorial experiments; Taguchi orthogonal arrays Available in digital repository of ČVUT.
Comparison of Different Approaches of Manufacturing Process Optimization

There are many process variables, which more or less influence quality of a manufacturing process, and there are many parameters of a product, which constitute its quality. The control of variables of ...

Mach, Pavel; Barto, Seba
České vysoké učení technické v Praze, 2010

Face-TLD: Tracking-Learning-Detection applied to faces
Kalal, Zdenek; Mikolajczyk, Krystian; Matas, Jiří
2010 -
A novel system for long-term tracking of a human face in unconstrained videos is built on Tracking-Learning-Detection (TLD) approach. The system extends TLD with the concept of a generic detector and a validator which is designed for real-time face tracking resistent to occlusions and appearance changes. The off-line trained detector localizes frontal faces and the online trained validator decides which faces correspond to the tracked subject. Several strategies for building the validator during tracking are quantitatively evaluated. The system is validated on a sitcom episode (23 min.) and a surveillance (8 min.) video. In both cases the system detects-tracks the face and automatically learns a multi-view model from a single frontal example and an unlabeled video. Keywords: long-term face tracking; learning; detection; verification; real-time Available in digital repository of ČVUT.
Face-TLD: Tracking-Learning-Detection applied to faces

A novel system for long-term tracking of a human face in unconstrained videos is built on Tracking-Learning-Detection (TLD) approach. The system extends TLD with the concept of a generic detector and ...

Kalal, Zdenek; Mikolajczyk, Krystian; Matas, Jiří
České vysoké učení technické v Praze, 2010

Usability of Electrically Conductive Adhesives for Power Components Assembly
Mach, Pavel; Bušek, David; Ješ, Josef
2010 -
Sensitivity of the resistance of adhesive joints formed of frequently used electrically conductive adhesives with isotropic electrical conductivity (ICAs) to loading with short current pulses of high amplitude has been examined. It has been found that the resistance increases with the increase of pulses amplitude and with the temperature at which experiments are carried out. It is assumed that the increase is caused by the increase of the thickness of insulating barriers between particles caused with chemical products originated by temperature degradation of resin is surroundings of contacts between particles. Heating of contacts is caused with the passing current. Keywords: electrically conductive adhesives; adhesive joint; joint resistance Available in digital repository of ČVUT.
Usability of Electrically Conductive Adhesives for Power Components Assembly

Sensitivity of the resistance of adhesive joints formed of frequently used electrically conductive adhesives with isotropic electrical conductivity (ICAs) to loading with short current pulses of high ...

Mach, Pavel; Bušek, David; Ješ, Josef
České vysoké učení technické v Praze, 2010

Image Matching and Retrieval by Repetitive Patterns
Doubek, Petr; Matas, Jiří; Perd’och, Michal; Chum, Ondřej
2010 -
Detection of repetitive patterns in images has been studied for a long time in computer vision. This paper discusses a method for representing a lattice or line pattern by shift-invariant descriptor of the repeating element. The descriptor overcomes shift ambiguity and can be matched between different a views. The pattern matching is then demonstrated in retrieval experiment, where different images of the same buildings are retrieved solely by repetitive patterns. Keywords: repetitive patterns; image retrieval Available in digital repository of ČVUT.
Image Matching and Retrieval by Repetitive Patterns

Detection of repetitive patterns in images has been studied for a long time in computer vision. This paper discusses a method for representing a lattice or line pattern by shift-invariant descriptor ...

Doubek, Petr; Matas, Jiří; Perd’och, Michal; Chum, Ondřej
České vysoké učení technické v Praze, 2010

Construction of Precise Local Affine Frames
Mikulik, Andrej; Matas, Jiří; Perd’och, Michal; Chum, Ondřej
2010 -
We propose a novel method for the refinement of Maximally Stable Extremal Region (MSER) boundaries to sub-pixel precision by taking into account the intensity function in the 2 × 2 neighborhood of the contour points. The proposed method improves the repeatability and precision of Local Affine Frames (LAFs) constructed on extremal regions. Additionally, we propose a novel method for detection of local curvature extrema on the refined contour. Experimental evaluation on publicly available datasets shows that matching with the modified LAFs leads to a higher number of correspondences and a higher inlier ratio in more than 80% of the test image pairs. Since the processing time of the contour refinement is negligible, there is no reason not to include the algorithms as a standard part of the MSER detector and LAF constructions. Keywords: discretized contour; contour refinement; curvature estimation; curvature extrema Available in digital repository of ČVUT.
Construction of Precise Local Affine Frames

We propose a novel method for the refinement of Maximally Stable Extremal Region (MSER) boundaries to sub-pixel precision by taking into account the intensity function in the 2 × 2 neighborhood of the ...

Mikulik, Andrej; Matas, Jiří; Perd’och, Michal; Chum, Ondřej
České vysoké učení technické v Praze, 2010

Forward-Backward Error: Automatic Detection of Tracking Failures
Kalal, Zdenek; Mikolajczyk, Krystian; Matas, Jiří
2010 -
This paper proposes a novel method for tracking failure detection. The detection is based on the Forward-Backward error, i.e. the tracking is performed forward and backward in time and the discrepancies between these two trajectories are measured. We demonstrate that the proposed error enables reliable detection of tracking failures and selection of reliable trajectories in video sequences. We demonstrate that the approach is complementary to commonly used normalized cross-correlation (NCC). Based on the error, we propose a novel object tracker called Median Flow. State-of-the-art performance is achieved on challenging benchmark video sequences which include non-rigid objects. Available in digital repository of ČVUT.
Forward-Backward Error: Automatic Detection of Tracking Failures

This paper proposes a novel method for tracking failure detection. The detection is based on the Forward-Backward error, i.e. the tracking is performed forward and backward in time and the ...

Kalal, Zdenek; Mikolajczyk, Krystian; Matas, Jiří
České vysoké učení technické v Praze, 2010

Tracking the Invisible: Learning Where the Object Might be
Grabner, Helmut; Matas, Jiří; Van Gool, Luc; Cattin, Philippe
2010 -
Objects are usually embedded into context. Visual context has been successfully used in object detection tasks, however, it is often ignored in object tracking. We propose a method to learn supporters which are, be it only temporally, useful for determining the position of the object of interest. Our approach exploits the General Hough Transform strategy. It couples the supporters with the target and naturally distinguishes between strongly and weakly coupled motions. By this, the position of an object can be estimated even when it is not seen directly (e.g., fully occluded or outside of the image region) or when it changes its appearance quickly and significantly. Experiments show substantial improvements in model-free tracking as well as in the tracking of “virtual” points, e.g., in medical applications. Available in digital repository of ČVUT.
Tracking the Invisible: Learning Where the Object Might be

Objects are usually embedded into context. Visual context has been successfully used in object detection tasks, however, it is often ignored in object tracking. We propose a method to learn supporters ...

Grabner, Helmut; Matas, Jiří; Van Gool, Luc; Cattin, Philippe
České vysoké učení technické v Praze, 2010

Unsupervised Discovery of Co-occurrence in Sparse High Dimensional Data
Chum, Ondřej; Matas, Jiří
2010 -
An efficient min-Hash based algorithm for discovery of dependencies in sparse high-dimensional data is presented. The dependencies are represented by sets of features co-occurring with high probability and are called co-ocsets. Sparse high dimensional descriptors, such as bag of words, have been proven very effective in the domain of image retrieval. To maintain high efficiency even for very large data collection, features are assumed independent. We show experimentally that co-ocsets are not rare, i.e. the independence assumption is often violated, and that they may ruin retrieval performance if present in the query image. Two methods for managing co-ocsets in such cases are proposed. Both methods significantly outperform the state-of-the-art in image retrieval, one is also significantly faster. Available in digital repository of ČVUT.
Unsupervised Discovery of Co-occurrence in Sparse High Dimensional Data

An efficient min-Hash based algorithm for discovery of dependencies in sparse high-dimensional data is presented. The dependencies are represented by sets of features co-occurring with high ...

Chum, Ondřej; Matas, Jiří
České vysoké učení technické v Praze, 2010

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